UNIVERSITY    OF    CALIFORNIA     AGRICULTURAL    EXPERIMENT  STATION 

^^».   .    -.«.-     «.-     .  ^_.^.  ..  -^.  .n-  BENJ.    IDE    WHEELER,    PRESIDENT 

COLLEGE   OF  AGRICULTURE 

THOMAS    FORSVTH    HUNT,    Dean  and  Director 
BERKELEY  H.    E.   VAN    NORMAN.    Vice-Director    and    Dean 

University  Farm  School 


CIRCULAR  No.  160 
(March,  1917) 

LETTUCE  GROWING  IN  CALIFORNIA 

By  STANLEY  S.  KOGEES 


CONTENTS  PAGE 

Classification  of  Lettuce 1 

Importance  of  the  Industry  in  California 2 

Lettuce   Growing   Districts  in   California 2 

Cost  of  Production,  Yields  and  Profits 2 

Cultural  Eequirements  5 

Soil    5 

Moisture   5 

Climate   5 

Preparation   of   the   Soil 5 

Planting  7 

Field  Cultivation   9 

Harvesting  12 

Packing  for  Shipment 13 

Varieties  14 

Crop  Troubles  15 

CLASSIFICATION  OF  LETTUCE 

There  are  several  classifications  of  lettuce,  depending  upon  the 
character  of  the  plant,  flavor,  and  cultural  requirements.  Professor 
W.  W.  Tracy1  has  classified  lettuce  as  follows :  The  cos,  distinguished 
by  its  upright  habit  and  long  leaves;  the  butter,  distinguished  by 
its  buttery  flavor;  and  the  crisp,  distinguished  by  its  hard,  crisp 
texture.  The  cos  has  been  subdivided  into  the  self-closing  and  loose- 
closing  division.  The  former  is  capable  of  producing  a  satisfactory 
leaf  without  tying,  the  latter  requires  tying.  The  butter  and  crisp 
classes  are  separated  into  cabbage-heading  varieties,  or  those  having 
solid  heads,  and  the  bunching,  or  those  which  do  not  form  solid  heads. 
There  are  other  classifications  influenced  by  the  soil  requirements  and 
season  of  growth,  such  as  Winter  lettuce,  which  can  withstand  low 
temperatures  and  is  rather  slow  growing ;  Spring  lettuce,  which  heads 
rapidly,  and  Summer  lettuce,  which  will  endure  the  heat  with  less 
degree  of  injury  than  either  of  the  above. 


For  the  California  grower,  lettuce  may  be  divided  into  two  classes, 
the  large  solid-head  and  the  loose-head.  The  large  solid-head  varieties 
may  be  subdivided  according  to  their  cold  and  heat-resistant  qualities. 
As  an  example,  the  Los  Angeles  variet}^  has  the  former  quality  and 
the  Iceberg  the  latter. 

IMPORTANCE  OF  LETTUCE  GROWING  IN  CALIFORNIA 
The  recent  development  of  the  lettuce-growing  industry  in  Cali- 
fornia has  been  very  rapid.  The  acreage  devoted  to  the  production  of 
this  crop  has  increased  from  700  acres  in  1911  to  2000  acres  in  1916. 
Although  lettuce  was  grown  in  California  prior  to  1911,  the  crop  was 
consumed  principally  in  the  local  markets.  During  the  past  few  years 
a  heavy  demand  for  California-grown  lettuce  has  been  established 
throughout  the  United  States.  This  is  due  largely  to  the  superior 
quality  of  the  crop  and  to  the  favorable  climatic,  soil,  and  moisture 
conditions  which  are  found  in  many  parts  of  the  state. 

The  future  of  the  California  lettuce  industry  seems  promising  as 
the  eastern  demand  is  increasing  so  rapidly  that  it  is  sometimes  dif- 
ficult to  supply  it  adequately. 

LOCATION  OF  LETTUCE-PRODUCING  CENTERS  IN  CALIFORNIA 
The  principal  lettuce-growing  district  of  California  is  near  Los 
Angeles.  This  section  produces  large  quantities  of  lettuce  throughout 
the  year  and.  especially  during  the  winter.  It  is  estimated  by  the  Los 
Angeles  Chamber  of  Commerce  that  the  production  of  lettuce  in  Los 
Angeles  County  during  1916  amounted  to  900  acres,  with  an  output 
of  399,465  crates.  The  second  section  of  importance  is  located  near 
San  Francisco,  Sacramento,  and  Stockton.  During  the  season  1916, 
200  acres  of  lettuce  were  grown  in  the  vicinity  of  San  Francisco  and 
approximately  the  same  amount  was  produced  at  Sacramento.  Aside 
from  the  above  mentioned  localities  this  vegetable  is  grown  success- 
fully in  many  other  parts  of  the  state,  and  there  is  probably  not  a 
county  in  which  it  is  not  produced,  at  least  in  small  amounts,  during 
some  season  of  the  year. 

COST  OF  PRODUCTION 
The  cost  of  production  is  largely  dependent  upon  the  character  of 
the  soil,  season  of  the  year,  experience  of  the  grower  and  the  area 
planted.     The  following  cost-per-acre  data  have  been  secured  from 
several  experienced  growers  and  at  the  University  Farm  Garden. 


lAmerican  Varieties  of  Lettuce.     United  States  Department  of  Agriculture. 
Bulletin  69,  p.  12. 


Per   acre 

Plowing  12  in.  deep  $  3.00 

Harrowing    .30 

Clod  mashing .50 

Constructing  raised  beds  10.00 

Seed    (3   lb.    @   $2.50)  7.50 

Growing  plants  (in  seed  beds)  2.00 

Eemoving  from  seed  bed  and  transplanting  to  field  ....  20.00 

Hoeing  once   8.00 

Irrigating  four  times  8.40 

Harvesting   and   crating    (2000   doz.)  13.50 

Total    $73.20 

Several  of  the  above  costs  are  variable.  If  the  raised  beds  are 
made  by  hand  the  cost  would  vary  from  $25  to  $30,  instead  of  $10. 
During  certain  seasons  of  the  year  one  irrigation  would  be  sufficient 
instead  of  four.  In  figuring  the  labor  costs  it  is  assumed  that  the 
laborer  will  receive  twenty-five  cents  per  hour,  nine  hours  constituting 
a  working  day. 


YIELDS  AND  PRICES  RECEIVED 

The  yields  vary  from  1500  dozen  to  2500  dozen  marketable  heads 
per  acre,  with  an  average  yield  of  2000  dozen.  Growers  who  ship  to 
wholesale  houses  receive  eight  to  twenty  cents  per  dozen  heads,  the 
usual  price  varying  from  ten  to  fifteen  cents. 

In  table  I  will  be  found  the  average  monthly  quotations  for  lettuce 
on  the  Los  Angeles  market  from  1911  to  1915,  inclusive.2  These  fig- 
ures represent  the  prices  which  the  wholesale  broker  quotes  to  the 
retail  buyer. 


Table  I 

Month 
January 

Year 
1911 
1912 

Av 
pei 

.  price 
■  crate 

$   .80 
1.37 

Month 
July 

Year 
1911 
1912 

Av.  price 
per  crate 

1.00 
.82 

1913 

1.04 

1913 

.96 

1914 

.95 

1914 

.98 

1915 

.87 

1915 

1.05 

February 

1911 
1912 

1.00 
1.27 

August 

1911 
1912 

1.00 
.95 

1913 

1.16 

1913 

.87 

1914 

.93 

1914 

.94 

1915 

.81 

1915 

1.10 

2  Compiled  by  Professor  A.  T.  Potts  of  the  Texas  Agricultural  College,  while 
studying  at  the  University  of  California. 


Month 

Year 

Av.  price 
per  crate 

Month 

Year 

Av.  price 
per  crate 

March 

1911 

1.15 

September 

1911 

1.19 

1912 

1.12 

1912 

.95 

1913 

1.07 

1913 

.95 

1914 

1.25 

1914 

.91 

1915 

.94 

1915 

1.14 

April 

1911 

$1.15 

October 

1911 

.99 

1912 

.96 

1912 

.82 

1913 

.92 

1913 

.53 

1914 

.94 

1914 

.78 

1915 

.85 

1915 

1.00 

May 

1911 

1.69 

November 

1911 

1.12 

1912 

.82 

1912 

.71 

1913 

.80 

1913 

.53 

1914 

.83 

1914 

.80 

1915 

.80 

1915 

1.05 

June 

1911 

.82 

December 

1911 

1.08 

1912 

.82 

1912 

.72 

1913 

.69 

1913 

.64 

1914 

1.00 

1914 

1.02 

1915 

•      .85 

1915 

1.10 

Average  price  of  lettuce  during  five  years,  1911-1915  inclusive, 
compiled  from  table  I. 

Table  II 


Av.  price 

Av.  price 

Month 

per  crate 

Month 

per  crate 

January 

$1.01 

July 

.82 

February 

1.03 

•  August 

.84 

March 

1.11 

September 

.91 

April 

.96 

October 

.96 

May 

.99 

November 

.97 

June 

.84 

December 

1.03 

It  will  be  noted  that  the  highest  prices  are  received  from  Novem- 
ber to  March,  inclusive,  and  especially  from  December  to  March.  The 
demand  for  California  lettuce  is  heaviest  during  these  months  for 
long-distance  shipments  to  the  colder  sections  of  the  United  States. 
During  the  summer  months  the  eastern  demand  for  California  lettuce 
is  comparatively  small,  due  to  the  large  amount  of  local  lettuce  in 
those  markets. 

Estimating  the  crop  to  be  2000  dozen  heads  and  the  price  at  12% 
cents  per  dozen,  the  grower  would  receive  a  gross  income  of  $250  per 
acre,  and  a  net  income  of  $176.80.  Considering  that  the  land  is  in 
use   only   three   to   four   months   this   would   appear   to   be   one   of 


the  most  satisfactory  vegetables  for  the  commercial  and  home  garden. 
It  will  be  understood  that  such  returns  are  obtained  only  under 
favorable  conditions  by  experienced  growers. 


CULTURAL  REQUIREMENTS 

Soil. — Lettuce  is  very  exacting  as  to  soil  requirements  and  is  best 
suited  to  a  rich  light  loam.  It  should  never  be  planted  on  soils  of 
poor  quality,  for,  although  the  plants  will  grow,  the  texture  of  the 
leaves  will  be  tough  and  the  heads  small,  both  of  which  are  very 
undesirable  qualities. 

Moisture. — Lettuce  requires  considerable  soil  moisture  throughout 
its  entire  growing  period,  making  irrigation  necessary  except  during 
the  rainy  season.  It  is,  however,  easily  ruined  by  an  excess  of  water 
which  makes  possible  a  stem  rot  on  the  plants. 

Climate. — Lettuce  is  a  hardy  vegetable  and  will  stand,  without 
injury,  a  low  degree  of  temperature.  Under  this  condition,  however, 
the  growth  of  the  plant  stops  and  a  moderate  temperature  is  desirable 
while  the  plants  are  growing.  This  crop  will  stand  cold  much  better 
than  heat,  making  it  impossible  to  produce  lettuce  of  good  quality 
during  the  summer  in  many  of  the  interior  valleys  of  the  state.  When 
the  weather  is  too  hot  and  dry  the  plants  will  produce  seed  instead 
of  heads. 


PREPARATION  OF  THE  SOIL 

At  the  time  of  planting  the  soil  should  be  in  the  finest  possible 
condition  and  free  from  all  weed  growth.  Many  growers  apply  from 
fifteen  to  twenty-five  tons  of  manure  per  acre.  This  should  be  applied 
long  enough  in  advance  of  planting  so  that  it  may  be  plowed  under 
and  completely  rotted  by  the  time  the  field  is  ready  for  use.  In  the 
fall  before  the  rains  have  commenced,  the  field  should  be  heavily 
irrigated  before  plowing,  but  in  the  winter  and  spring  months  there 
is  generally  a  sufficient  amount  of  moisture  without  irrigation.  After 
the  soil  has  been  worked  into  good  condition,  raised  beds  or  ridges 
should  be  made  either  by  the  use  of  a  hand  hoe,  or  a  special  cultivator 
attachment.  The  latter  implement  is  generally  used  where  a  large 
area  is  planted  and  the  former  where  a  small  amount  is  grown.  The 
beds  should  be  from  twelve  to  eighteen  inches  wide,  four  to  six  inches 
high,  and  the  spaces  between  them  ten  to  fifteen  inches.  After  the 
beds  have  been  prepared  the  field  should  be  irrigated  a  few  days 
before  planting  in  order  that  the  soil  ma}^  settle. 


Fig.  1. — Constructing  raised  beds. 


Fig.    2. — After    the    raised    bods    have    been    roughly    constructed,    they    may 
smoothed  over  with  a  garden   rake  and   irrigated. 


be 


PLANTING  AND  CARE  OF  THE  SEED  BEDS 
The  time  of  planting  is  governed  entirely  by  the  climate,  and  it 
is  very  important  that  the  grower  be  acquainted  with  his  local  climatic 
conditions  before  growing  this  crop.  For  the  interior  valleys  of  the 
state  the  planting  season  generally  starts  during  the  last  of  August 
and  continues  until  the  first  of  March.  Many  growers  make  a  first 
planting  of  the  seed  from  the  middle  to  the  last  of  August,  a  second 
in  October,  and  a  third  during  January  or  February.  Along  the 
coast,  where  the  climate  is  more  moderate,  it  is  possible  to  grow 
lettuce  successfully  during  any  month  of  the  year. 


Fig.  3. — Sunken  seed  beds. 

There  are  two  methods  for  growing  lettuce,  both  of  which  are  used 
extensively  in  California.  The  first  is  by  planting  the  seed  directly 
in  the  field,  sowing  it  in  drills  on  the  borders  of  the  raised  beds; 
the  second  is  to  sow  in  seed  beds  and  transplant  the  young  plants  into 
the  field  when  they  have  attained  the  desired  size. 

There  are  several  forms  of  seed  beds  in  use,  the  most  common 
being  the  sunken  beds,  which  vary  from  three  to  six  feet  in  width 
and  eight  to  fifteen  feet  in  length.  The  earth  taken  from  these  beds 
is  hoed  up  to  form  a  levee  around  each  in  order  to  aid  in  irrigating. 
Before  planting,  a  heavy  coating  of  well-rotted  manure  should  be 
spaded  under  and  the  soil  should  be  heavily  irrigated  just  previous 
to  seeding.     The  seed  may  either  be  broadcast  or  sown  in  drills,  and 


8 

immediately  covered  with  one-half  inch  of  earth.  If  the  soil  is  of  a 
heavy  nature  so  that  it  is  liable  to  run  together  and  bake  when  irri- 
gated, a  thin  coating  of  well-rotted,  screened  stable  manure  should 
be  applied  on  the  surface  before  seeding.  It  will  aid  the  seed  in 
germinating  if  strips  of  burlap  be  placed  on  the  soil  and  allowed  to 
remain  until  the  young  plants  are  appearing  at  the  surface.  In 
removing  this  covering  the  young  plants  should  not  be  exposed  too 
suddenly  to  the  light.  During  the  warm  months  it  is  often  necessary 
to  irrigate  several  times  before  the  young  plants  appear.  The  water 
may  be  applied  either  through  a  sprinkler  or  by  flooding,  using  only 
a  small  stream  so  that  the  tender  seedlings  may  not  be  injured.  The 
amount  of  irrigation  which  the  beds  will  need  depends  largely  upon 
the  character  of  the  soil  and  the  season  of  the  year.  During  the  early 
fall  the  beds  are  often  irrigated  three  or  four  times  a  week,  while  later 
in  the  season  one  or  two  irrigations  will  prove  sufficient.  When  the 
plants  are  one  and  a  half  to  two  inches  tall  the  beds  may  be  weeded 
and  the  plants  thinned,  leaving  the  distance  between  every  two  not 
less  than  one  inch. 

Under  ordinary  conditions  the  plants  should  remain  in  the  seed 
beds  six  weeks,  although  the  time  required  will  vary  from  one  to 
two  months  with  the  season  of  the  year  and  care  of  the  plants.  When 
planting  directly  in  the  field  three  to  four  pounds  of  seed  will  be 
sufficient  for  one  acre ;  .at  the  University  Farm  Garden,  2600  square 
feet  of  seed'  beds  raised  a  sufficient  number  of  plants  for  one  acre  in 
the  field. 

When  quick-growing  plants  are  desired  the  seed  should  be  sown 
in  hotbeds  in  preference  to  the  open  beds.  This  form  of  bed  is 
occasionally  used  during  the  winter  and  early  spring. 

Removing  the  Plants. — Plants  may  be  transplanted  when  they 
are  from  two  to  four  inches  tall,  the  larger  size  being  preferable 
during  the  warm  weather.  Before  removing,  the  plants  should  be 
hardened  by  stopping  the  irrigation  a  few  days  in  advance  so  that 
their  growth  may  be  checked.  A  few  hours  before  the  plants  are  to 
be  removed  they  should  be  thoroughly  irrigated  in  order  that  as  much 
soil  and  as  many  fibrous  roots  as  possible  may  be  taken  up  with  the 
seedlings.  There  are  two  methods  for  removing  the  plants.  Those 
who  have  had  considerable  experience  may  pull  them  by  hand.  Those 
with  limited  experience,  and  especially  if  the  soil  is  of  a  heavy  nature, 
should  dig  them  with  the  aid  of  a  trowel  or  shovel.  The  plants  should 
be  constantly  covered,  after  being  removed,  until  they  are  planted  in 
the  field,  for  if  exposed  to  the  sun  many  of  the  small  roots  will  be 
killed.     If  the  seedlings  are  too  large  the  leaves  and  roots  should  be 


cut  back.     The  best  size  of  plant  for  transplanting  is  one  having  a 
top  three  inches  tall  and  roots  two  inches  long. 

FIELD  CULTIVATION 

Planting. — The  distance  between  the  plants  in  the  field  varies  from 
eight  to  fifteen  inches.  Where  a  variety  producing  large  heads  is 
grown,  such  as  the  Los  Angeles,  the  plants  should  not  be  less  than 
twelve  inches  apart  in  rows  twelve  inches  apart,  but  if  a  smaller 
variety  is  used  the  spaces  between  the  plants  may  be  slightly  reduced. 
If  the  seed  has  been  sown  directly  in  the  field  the  plants  should  be 


Fig.  4. — Setting  lettuce  plants  in  the  field. 


thinned  when  they  are  from  two  to  four  inches  tall,  and  the  vacant 
spaces  filled  with  those  which  have  been  removed  while  thinning. 

Irrigation. — A  few  days  before  planting,  the  fieldx  should  be  irri- 
gated in  order  to  settle  the  earth  in  the  raised  beds,  and  to  show  how 
far  up  on  them  the  water  will  come.  If  this  is  not  known  many  of  the 
plants  will  be  so  high  on  the  beds  that  they  will  not  receive  sufficient 
water,  while  others  will  be  so  low  that  they  will  be  injured  from  an 
over-supply.  As  soon  as  the  plants  have  been  transplanted  the  field 
should  be  thoroughly  irrigated,  and  it  is  especially  important  while 
they  are  young  that  frequent  irrigations  be  given.     In  applying  the 


10 

water  care  should  be  taken  that  it  is  not  allowed  to  flow  over  the  tops 
of  the  beds,  and  it  will  be  found  much  more  satisfactory  to  use  a  small 
stream,  allowing  it  to  run  between  the  beds  slowly,  and  thoroughly 
soaking  into  them,  than  a  larger  stream  flowing  more  rapidly. 

The  number  of  irrigations  which  the  field  will  require  can  only  be 
determined  by  the  condition  of  the  plants.  It  is  sometimes  desirable 
to  irrigate  every  week  throughout  the  season,  while  under  other  con- 
ditions one  or  two  irrigations  will  be  sufficient.  There  should  always 
be  an  adequate  amount  of  moisture  in  the  soil  from  the  time  the 
plants  have  commenced  to  head  until  they  have  matured,  because  the 


Fig.  5. — ' '  Scandigie ' '  used  for  transplanting. 

character  and  size  of  the  heads  is  influenced  to  a  great  extent  by  the 
quantity  of  soil  moisture  present. 

During  the  late  spring  if  it  is  desirable  to  hold  the  crop  in  the 
field  for  a  short  time  after  it  has  matured,  no  more  water  should  be 
applied,  as  it  will  increase  the  liability  of  the  plants  going  to  seed. 

Cultivation. — When  raised  beds  are  used  all  of  the  cultivation  will 
have  to  be  done  by  hand,  and  the  number  of  times  which  the  field 
should  be  hoed  will  vary  from  one  to  five  during  the  season.  This  will 
depend  upon  the  character  of  the  soil,  the  weed  growth,  and  the 
thoroughness  with  which  the  beds  have  been  made  and  irrigated.  The 
soil  need  not  be  hoed  between  the  beds  unless  there  is  a  heavy  growth 
of  weeds.     Occasionally  water  will  flow  over  the  tops  of  the  beds  and 


11 


1 

1 

■ ;  s  «  s 

I  ! 

rj£BF-     . 

P. '  ^'V  'HI    •     :         1 

-..:•&> 

Fig.  6. — Lettuce  plants  should  be  set  at  the  edge  of  the  moist  earth. 


Fig.    7.- — When    irrigating   lettuce   water    should   never    be    allowed    to    cover    the 

plants. 


12 


these  low  places  should  be  hoed  after  each  irrigation  if  the  soil  has  a 
tendency  to  run  together,  for  the  growth  of  the  plants  will  be  retarded 
if  the  earth  close  to  them  is  allowed  to  harden. 

HARVESTINGS 
The  time  required  to  mature  a  crop  of  lettuce  varies  with  the 
season,  the  character  of  the  soil,  and  the  care.  Plants  set  in  the  field 
during  September  should  mature  during  November  and  December. 
Plants  set  in  the  field  during  November  will  mature  from  February 
to  April,  inclusive,  and  those  transplanted  during  February  and 
March  will  mature  from  April  to  June. 


•-"*       '        "      "*** 

*,-:    .;-» 

^j^g^^jV^%4S^^'^ 

'!&.                                         *             SSl  I  ;%rl 

Fig.  8. — Lettuce  should  remain  in  the  field  until  the  heads  have  fully  matured. 

The  period  of  growth  at  which  the  crop  should  be  harvested  de- 
pends largely  upon  the  season,  market  requirements  and  prices.  The 
California  market  demands  a  large  solid  head  and  the  crop  should 
remain  in  the  field  until  it  has  reached  this  condition. 

In  harvesting  it  will  be  found  most  efficient  to  employ  three  men ; 
one  man  cutting  and  two  placing  the  heads  in  piles.  During  the 
spring  when  the  weather  is  warm  it  is  best  to  cut  the  lettuce  early  in 
the  morning  while  it  is  cool  and  place  it  in  the  shade  during  the  heat 
of  the  day,  unless  it  is  possible  to  ship  immediately.  The  crop  should 
never  be  cut  when  the  heads  are  wet,  as  they  will  heat  and  quickly  rot 


3  The   following   calendar   is   applicable   to   the   interior   valleys   of   the   state, 
and  especially  to  central  California. 


13 

when  packed  in  that  condition.  The  field  is  generally  gone  over  from 
three  to  five  times  during  the  cutting  season,  and  the  heads  should  be 
cut  at  the  base,  using  a  knife  having  a  blade  ten  to  twelve  inches  in 
length.  After  the  crop  has  been  harvested  it  should  be  handled  very 
carefully  and  sold  as  soon  as  possible. 

PACKING  FOR  SHIPMENT 
Lettuce  should  always  be  packed  for  shipment  in  crates,  especially 
when  disposal  is  to  be  made  at  a  considerable   distance   from  the 


Fig.  9. — Lettuce  packed  in  the  field  for  local  market  or  packing  house. 


garden.  There  are  three  sizes  of  crates  commonly  used:  the  Los 
Angeles  crate,  which  holds  from  three  to  five  dozen  and  is  twenty- 
four  inches  in  length,  eighteen  inches  in  width  and  thirteen  inches  in 
height;  the  pony  crate,  which  holds  two  dozen  heads  of  ordinary  size 
lettuce  and  is  about  one-half  as  large  as  the  Los  Angeles  crate;  and 
the  field  crate,  which  is  about  twice  as  large  as  the  Los  Angeles  and 
holds  about  eight  dozen  heads  of  ordinary  size  lettuce.  The  Los 
Angeles  and  pony  crates  are  most  commonly  used  for  long-distance 
shipments. 

After  the  lettuce  is  cut  it  is  hauled  directly  to  the  packing  house 
where  it  is  sorted,  trimmed  and  repacked.  That  which  is  to  be  shipped 
a  considerable  distance,  and  especially  during  warm  weather,  should 


14 

always  be  protected  from  the  heat;  a  layer  of  chopped  ice  should  be 
placed  between  the  bottom  and  the  second  layer  of  lettuce,  and  one 
on  the  top  layer.  If  the  pony  crate  is  used  the  ice  is  put  on  the  top 
layer  only.  The  inside  of  the  crates  should  be  lined  with  heavy  paper, 
which  prevents  the  contents  from  drying  and  aids  in  keeping  it  cool. 
Lettuce  is  shipped  in  iced  or  refrigerator  cars,  the  temperature  of 
which  should  be  kept  as  even  as  possible. 

In  filling  the  crates,  the  bottom  layer  should  be  packed  with  the 
stem  ends  down  and  the  others  reversed,  thus  protecting  the  heads 
from  injury  in  transit.  After  the  crates  are  packed  they  are  placed 
immediately  on  cars  and  rushed  to  their  destination.  An  ordinary 
sized  car  holds  from  300  to  310  crates. 


in 

IB 

/§P^;^$ 

^mL        '.'..'._  ill 

Fig.    10. — Lettuce  re-packed  for  long   distance  shipment   and   empty   crate   lined 
with  paper  preparatory  to  packing. 


VAKIETIES 

There  are  a  large  number  of  varieties  of  lettuce  under  cultivation. 
Robinson  in  his  book,  '  -  The  Vegetable  Garden, ' '  names  over  one  hun- 
dred and  twenty-five.4  At  the  University  Farm  Vegetable  Garden 
during  the  past  season,  eighty  different  varieties  were  grown,  most  of 
which  did  well  under  our  conditions.  Of  this  large  number,  however, 
there  are  a  comparatively  few  which  meet  the  demand  of  the  Califor- 
nia buyers.  The  four  leading  varieties  which  are  now  being  produced 
in  this  state  are  the  Los  Angeles  or  New  York  Market,  the  Iceberg, 
the  California  Cream  Butter,  and  the  Hansen. 

Los  Angeles. — This  variety  is  by  far  the  most  popular  and  is  especially 
adapted  for  long-distance  shipments.  The  head  is  large,  solid,  tender,  an  ex- 
cellent shipper,  and  matures  quickly.     The  outer  leaves  are  dark  green  in  color, 


4  W.  W.  Robinson,  ' '  The  Vegetable  Garden, ' '  t>p.  362-399. 


15 

but  the  head  is  well  bleached  and  excellent  in  flavor.  This  variety  will  withstand 
cold  without  injury  but  is  not  adapted  to  maturing  during  hot  weather  as  it 
quickly  goes  to  seed. 

Iceberg. — This  variety  is  grown  extensively  and  is  especially  adapted  to 
maturing  during  the  hot  weather.  In  size  and  general  appearance,  it  is  quite 
similar  to  the  Los  Angeles  variety,  the  main  difference  being  a  reddish  tinge 
on  the  edges  of  the  leaves.     This  is  a  good  shipping  variety  . 

California  Cream  Butter. — This  variety  is  commonly  grown  and  is  similar 
to  the  Big  Boston.  It  has  a  rich  creamy  taste  from  which,  presumably,  it 
derived  its  name.  The  head  is  light  green  and  tinged  with  brown.  The  outer 
leaves  are  slightly  spotted  with  inconspicuous  brown  spots. 

Hansen. — This  is  a  desirable  variety  for  local  market.  The  leaves  are  a 
lighter  green  than  those  of  the  Los  Angeles.  The  heads  are  solid  and  have  a 
good  flavor. 


Fig.  11. — Los  Angeles. 


CROP  TROUBLES 

Securing  a  Stand  of  Plants. — It  is  ©ften  difficult,  especially  during 
hot  weather,  to  secure  a  satisfactory  stand,  either  when  planting 
directly  in  the  field  or  when  sowing  in  seed  beds.  Aside  from  the 
climatic  influence,  the  germinating  power  of  the  seed,  over-irrigation, 
or  applying  insufficient  quantities  of  water  are  often  responsible  for 
this  condition.  In  controlling  this  trouble  the  grower  should  de- 
termine which  of  the  foregoing  causes  is  responsible  and  remedy  it 
if  possible.  (For  detailed  directions  for  the  construction  and  care 
of  the  seed  bed,  see  page  7.) 

Stem  Rot. — This  disease  is  present  in  the  fields  during  winter  and 
early  spring ;  it  is  most  prevalent,  on  heavy  soils,  and  especially  severe 


16 

where  drainage  is  poor.  Soon  after  it  appears,  the  plants  will  become 
a  sickly  yellow  color  and  the  stems  will  rot  at  the  surface  of  the 
ground.  These  diseased  plants  may  appear  promiscuously  throughout 
the  field,  or  may  be  in  certain  well-defined  areas.  This  is  a  fungus 
disease  which  thrives  best  under  excessive  moisture  conditions.  For 
control  the  grower  should  improve  the  drainage  so  that  no  water  will 
be  allowed  to  stand  on  the  field,  and  the  beds  should  be  made  high 
enough  so  that  the  water  will  not  stand  directly  around  the  plants. 

Sunburn. — This  trouble  is  characterized  by  a  blackening  of  the 
edges  of  the  leaves  inside  the  heads.  It  is  often  impossible  to  know 
that  this  condition  exists  without  cutting  into  the  head.  Severe  losses 
are  sometimes  occasioned,  especially  in  the  crop  maturing  during  the 
late  spring.  Occasionally  these  affected  plants  will  rot  during  ship- 
ment. The  cause  is  a  period  of  excessive  hot  weather  from  the  time 
the  plants  are  half-grown  until  they  have  commenced  to  head.  Plant- 
ing in  the  fall  or  early  spring  will  largely  control  this  disease ;  if  the 
weather  is  very  hot  and  dry  during  the  spring  the  plants  should  be 
irrigated  frequently. 

Failure  to  Produce  Solid  Heads. — This  condition  is  caused  either 
by  a  poor  quality  of  seed,  an  insufficient  supply  of  moisture,  or  un- 
favorable climatic  conditions,  such  as  excessive  hot  weather  while  the 
plants  are  maturing.  This  may  be  largely  overcome  by  using  only 
well-selected  seed  and  applying  sufficient  moisture  at  the  time  the 
heads  are  maturing.  During  the  late  spring  when  the  weather  is 
hot  the  crop  should  be  harvested  immediately  after  the  heads  have 
matured. 


